A group of scientists are sent on a mission to destroy unstable planets. Twenty years into their mission, they have to battle their alien mascot as well as a "sensitive" and intelligent bombing device that starts to question the meaning of its existence.

When foreman Frank shows new employee Freddy a secret military experiment in a supply warehouse in Louisville, Kentucky, the two klutzes accidentally release a gas that reanimates corpses into flesh-eating zombies. As the epidemic spreads throughout the town, and the creatures satisfy their hunger in gory and outlandish ways, Frank and Freddy fight to survive with the help of their boss and a mysterious mortician.